A. Field of the Invention
The field of the present invention relates generally to devices for securing a trailer in place so as to prevent theft of the trailer. More specifically, this invention relates to devices for securing trailers by preventing movement of one or more of the trailer""s wheels. Even more specifically, this invention relates to theft deterrent devices used to prevent unauthorized movement of a trailer by preventing air from reaching, and thereby releasing, the trailer""s air brakes.
B. Background
Many persons utilize trailers for various applications, including trailers that are used to transport goods, vehicles, and other materials. Trailers commonly used in the trucking industry are very expensive. When used to transport certain expensive goods, such as electronics or cars, the content of the trailer can often far exceed the value of the trailer itself. However, while utilizing a trailer, the truck driver often needs to disconnect the trailer from the vehicle towing the trailer and leave the trailer at a specified location. All too often, unfortunately, thieves utilize the opportunity of a trailer left at a location, particularly if it is remote, to steal the trailer and its contents. Once the trailer is removed from its stored location and taken to a different location, the thieves are able to open the trailer and remove its contents. Due to the nature of the crime and the goods stored therein, it is often difficult for the owner to regain possession of his or her property, including the trailer itself.
Unauthorized movement or use, including theft, of trailers and their cargo is a major concern among those in the trucking industry (overall, loss of cargo has an estimated annual business impact of $30 to $60 billion). As security devices become more complicated and more expensive, thieves become more sophisticated and more resourceful, making protection of an unmanned trailer very difficult. While cars, trucks and other motorized vehicles require power control systems and steering mechanisms to operate, trailers generally have no such systems or mechanisms. As a result, it is generally easier to disable (i.e., make it difficult to move the vehicle without authorization) a motorized vehicle than it is to disable a non-motorized vehicle, such as a trailer, that relies on the movement of another vehicle for its own movement. The ability to hook-up to and move trailers makes it very difficult to disable them so as to prevent theft. Naturally, this makes it difficult and/or expensive to obtain insurance to protect against such losses.
While it is unlikely that any device can absolutely prevent theft of a vehicle or trailer in light of current technology and a determined thief, devices have been developed that, when properly used, deter the would be thief from stealing the vehicle, in part because of the amount of time and effort it takes to remove or get around the theft deterrent device. An example of devices that have been highly successful at accomplishing this objective are the various steering wheel lock devices that provide a bar across the steering wheel, making rotational movement of the steering wheel, and hence sustained movement of the vehicle, virtually impossible. While the steering wheel lock devices have worked well for self-propelled vehicles such as automobiles and trucks, there exists a need for a device that is specifically designed to allow the owner or driver of a trailer to leave the trailer in a designated location and prevent unauthorized movement of the trailer in order to protect the owner""s investment in the trailer and the goods stored therein.
To prevent theft of a trailer left or stored at a protected or unprotected location, trailer owners typically use mechanical locking devices, such as the gladhand and kingpin locks, that are designed to physically prevent hook-up to those trailer components. As those in the trucking industry know, experience has proven that these devices can be overcome relatively easily by the determined and resourceful thief. In addition, the devices are useless if the truck driver forgets to set the locks. Even when the driver does set the locks, problems can arise if the next authorized driver does not have the key and is forced to break the lock to move the trailer, thereby rendering the security system useless. In order to be able to locate a stolen truck, and thereby also serving as a theft deterrent, some trucking companies utilize satellite tracking devices attached to the trailer that enable the trucking company or law enforcement personnel to track the movement of the trailer. Unfortunately, satellite systems are very expensive and can be relatively easily disabled (i.e., with a screwdriver and hammer) due to the vulnerability of the antenna assembly.
Because trailers utilize compressed air-operated braking systems, theft deterrent devices have been developed that take advantage of that system. The typical trailer utilizes spring-biased parking brakes which require the introduction of air pressure to release the brakes. The parking brake system is configured such that the brakes are engaged by a spring to lock the trailer""s wheels when there is no air pressure in the air line to release the brakes. The tractor or truck used to haul the trailer includes an air compressor that provides compressed air to the trailer through a brake air line in order to release the brakes so as to allow movement of the trailer. When the driver releases the trailer from the truck, the disconnect of the brake air line from the compressor biases the spring to lock the wheels to prevent movement of the trailer.
Two such systems are described in U.S. Pat. No. 4,621,874 to Gustafsson and U.S. Pat. No. 5,145,240 to Harless, et al. The Gustafsson patent describes a vehicle theft device that utilizes a series of three-way valves and check valves to interact with the main and parking brake systems to prevent movement of a vehicle, primarily the tractor portion of a truck. The valves direct air pressure away from the drive axles and routes it to acuate the front brakes only. A major limitation with this type of device is that if there is a malfunction, then the front wheels can lock-up while the vehicle (and trailer) is moving. Vehicle accidents have resulted from such a malfunction. The Harless patent describes a valve assembly that interacts with a trailer""s air brake system to prevent movement of the trailer until someone manually releases the valve from inside the trailer. This system is primarily designed to prevent injury to workers while loading the trailer.
Although the various theft deterrent devices currently available have some ability to prevent theft of trailers, they have disadvantages and limitations that prevent wide acceptance or effective theft deterrence. What is needed, is an easy to use and effective theft deterrent device that allows a trailer owner to quickly and securely lock his or her trailer in place in order to prevent unauthorized movement of the trailer.
The trailer locking device of the present invention solves the problems identified above. That is to say, the present invention discloses a new and useful trailer locking device that effectively prevents theft of a trailer. The trailer locking device of the present invention is adaptable to new and existing trailers, is easy for the truck driver to engage and is difficult for the thief to overcome or disable.
In one embodiment, the trailer locking device of the present invention is a separate unit having a housing, a controller unit mounted in the housing, a control valve mounted in the housing and a control mechanism located outside the housing. The controller unit is connected to a power supply, such as a battery, which can be located in the housing and adapted for connection to an external power source, such as the electrical take-off from the tractor or truck pulling the trailer. A charging regulator can be used to ensure the battery is kept in a charged condition without overcharging. The control valve is electrically connected to the controller unit. The control valve inlet is configured for connection to a supply of compressed air and the outlet is in fluid communication, selectively, with the inlet so as to allow compressed air to vent from the control valve. The compressed air can vent to the inside of the housing or outside the housing. In the preferred embodiment, the control valve has a mechanism for activating the valve by selectively opening and closing the interior chamber between the inlet and the outlet. The activating mechanism can be an electric motor operatively connected to a shaft that is slidably disposed in the control valve. One or more limiting switches, electrically connected to the controller unit, are used to monitor and limit the movement of the shaft in the control valve. Pressure sensors are operatively engaged with the control valve and electrically connected to the controller unit. The control mechanism, which can be a keypad, keylock, radio controlled or other similar mechanisms, is electrically connected to the controller unit for selectively controlling the control valve.
In another configuration of the present invention, the trailer locking device is configured for use with a trailer having an internal cavity and a brake line connected to one or more compressed air-operated brakes. This locking device has a housing which is disposed in the internal cavity of the trailer, a controller unit mounted in the housing, a control valve mounted in the housing and a control mechanism (i.e., keypad, key lock, etc.) on the outside of the housing. The controller unit is connected to a power supply, which is preferably located inside the housing, and the control valve is electrically connected to the controller unit. The control valve inlet is pneumatically connected to the brake line between the supply of compressed air (i.e., from the tractor or truck) and the brakes. The control valve outlet is in fluid communication with the inlet so as to allow the compressed air to vent from the control valve to place the brakes in a locked condition when desired. The control mechanism is operatively connected to the controller unit for selectively controlling the control valve so as to change the condition of the control valve from the locked to the unlocked condition. Preferably, the control mechanism is located outside of the housing and attached to an outer wall of the internal cavity. Alternatively, the control mechanism can be radio controlled with the receiver in or near the housing to receive transmissions from other sources to lock or unlock the trailer.
In yet another configuration of the present invention, the trailer lock device is incorporated into a trailer having a brake line pneumatically connected to one or more compressed air-operated brakes. In this configuration, the housing could be eliminated if the controller unit, power supply and control valve are incorporated into the trailer itself. As with the other embodiments, the control valve is electrically connected to the controller unit and it has an inlet that is pneumatically connected to the brake line between a supply of compressed air and the brakes. The control valve outlet is in fluid communication with the inlet so as to allow compressed air to vent from the control valve to place the brakes in a locked condition. The control mechanism is operatively connected (i.e., by coaxial cable, other wiring, radio connection or etc.) to the controller unit for selectively controlling the control valve so as to change between the locked condition and an unlocked condition. The control valve can have an activating mechanism for activating the control valve by selectively opening and closing the communication between the inlet and the outlet. The activating mechanism can comprise an electric motor that is operatively connected to a shaft which is slidably disposed in the control valve. One or more limiting switches can be used to monitor and limit the amount of movement of the shaft in the control valve. Pressure sensors are operatively engaged in the control valve to signal the controller unit to vent air through the control valve.
Accordingly, the primary objective of the present invention is to overcome the disadvantages associated with presently available trailer theft deterrent devices and to provide a trailer theft deterrent system that is easy to use and effective to prevent theft of a trailer. It is also an important objective of the present invention to provide a trailer locking device that prevents compressed air from getting to the air-operated brakes by utilizing a valve disposed between the source of compressed air and the brakes to vent the compressed air when locking of the trailer is desired. It is also an important objective of the present invention to provide a trailer lock device having a controller unit and control valve mounted in a housing with an external control mechanism to allow the user to lock and unlock the device. It is also an important objective of the present invention to utilize one or more pressure sensors connected to a controller unit to determine when to lock the trailer""s brakes by venting air through the control valve. It is also an objective of the present invention to utilize the interior cavity places on a trailer to position the trailer locking device so as to make it more difficult to overcome the theft deterrent aspects thereof. The above and other objectives of the present invention will be explained in greater detail by reference to the attached figures and the description of the preferred embodiment which follows.